Nuclear Irradiation Of Biology To Improve Its Fixation Of High Concentration Of CO₂ From Exhaust Gas

Global warming caused by extensive CO2 emissions has become a significant problem for the life of people. The process of photosynthetic can change carbon dioxide into oxygen, so many natural creatures will absorb carbon dioxide during their growth. For microalgal higher solar energy conversion efficiency and higher growth rate, the biological sequestration of CO2 by photosynthetic microalgae is a promising approach of CO2 mitigation from different sources, including atmosphere, industrial exhaust gases, especially flue gas of coal-fired power plants. Nuclear irradiation combined with CO2 domestication was used to isolated more excellent microalgae species for CO2 fixation in this study. Furthermore, lettuce seeds were also mutated by nuclear irradiation to study biological carbon fixation technology from two angles in this study.Spirulina species were mutated by nuclear irradiation and domesticated with high concentrations of CO2 to improve biomass productivity and CO2 fixation. The biomass yield of Spirulina mutated by 9000 Gy of 60Co-γ irradiation was increased by 569%(to 2.39 g/L) under air bubbling in five days. The mutants were domesticated with gradually increased high concentrations of CO2, which increased the biomass yield by 290% to 3.87 g/L under CO2 concentration of 15 vol.%. Afterwards, lettuce seeds were mutated by nuclear irradiation, the biomass productivity and CO2 fixation rate were both the highest in lettuce seeds mutated using 30 Gy of 1377Cs γ irradiation and hydroponically grown in open air. Grana volume in the chloroplasts of fresh leaf materials obtained from eighteen-day-old plants mutated using 30 Gy was 3.35 times that of the one without irradiation. and wet weight increased by 22.3%(to 52.24 g) in 30 days.Based on the study of the growth rate of spirulina under different light intensity, the growth velocity was increased by 111.7%(to 1.44 g/(L*d)) under 12000lux compared to 60001ux. Through the spirulina medium regulator (sodium carbonate and sodium bicarbonate) optimization, found only when adding 0.1 mol/L sodium carbonate into medium got the highest growth rate(0.805g/(L*d)) and biomass yield(1.32g/L) under 15% CO2. Optimize the growth conditions of the lettuce grown from the irradiated seeds, when the mutants were domesticated with high concentrations of CO2 (from 1 vol.% to 5 vol.%), it turned out that the best CO2 concentration (3 vol.%) for lettuce yielded the biggest CO2 fixation rate and biomass productivity. At constant CO2 concentration of 3 vol.%, wet weight of lettuce increased by 74.6%(to 48.7 g) in 24 days.